The tune is called "Asteroids" by Pete Moore! It's not the original Pearl and Dean trademark music however. A version of The Acropolis appeared on screen accompanied by a rising chord sequence of chord 1, followed by chord 2 (minor), followed by chord 3, followed by chord 5 (7) followed by chord 1 at the 8ve to finish. (only if you're old enough to remember. I'm a sad old school music-teacher type, who used to go to the ABC cinema. Lothian Road, Edinburgh who knew the projection staff.
Cheers now,
Kenny Duncan.